Apparatus for working fused silica or the like.



No. 836,558. v PATENTED NOV. 20, 1906.. J. F. BOTTOMLEY & A. PAGET.

APPARATUS FOR WORKING FUSED SILICA OR THE LIKE.

APPLICATION FILED FEB-28.1906.

2 SHEETS-SHBET 1.

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6 we a W/ TN 5555. I wvmvrms No. 836,558. PATENTED NOV. 20, 1906.

J. F. BOTTOMLEY & A. PAGET.

APPARATUS FOR WORKING PUSED SILICA OR THE LIKE. APPLIGATION FILED FEB.28. 1906.

2 SHEETSSHEET 2- p RQTJZ p dz: Q 5 2 6 f ,5 5 6 A /e i e figi a rainJAMES FRANCIS BOTTOMLEY, or WALLSEND,- AND ARTHUR mom,

or NORTH GRAY, ENGLAND. I

APPARATUS FUR WORKHING FUSED SlLlGA OR THE LIKE.

T0 at whom it may concern: Be it known that we, JAMES FRANCIS Bor-TOMLEY, a resident of Wallsend-on-Tyne, in

the county of Northumberland, and ARTHUR. PAGET, a resident of NorthGray, in the county of Kent, England, subjects of His Majesty the Kingof Great Britain, have-invented a tic cylinder of fused silica formed byfusion of sand or other suitable form of silica round a central coreheated by the passage of an electric current. Where silica and fusedsilica are hereinafter referred to, the words are intended to cover notonly pure silica, but combinations of same or of other materials havingmelting-points above -1500 centi- -grade, at which theybecome plasticandvitreous.

To form the cylinder of plastic silica, we make use of a furnace soconstructed as to allow of a separation of the terminals from theheating-core after the completion of the fusion, so that the plasticsilica may be removed. and the heating-core withdrawn from the cylindereither before or after its removal from the furnace- The heating-core ispreferably formed of carbon or graphite and may be either solid orhollow and of any desired cross-section, according -to the size andnature of the product required.

In order to allow of theready Withdrawal .of the heating-core in thecase of a carbon or graphite core, the heating'is continued sufficientlyto allow of an initial separation between the core and the inner.surface of the plastic cylinder, which takes place on account of theformation of a small quantify of gas on the surface of the core.

In case the product is to take the form of a true cylinder specialprecautions are necessary in. order to avoid the tendency to theformation of a D-section. may be met by inclosing the material to beheated in such a way as to give uniform support to the plastic cylinderby preventing Specification of Letters Patent. Application filedFebruary 28. 1906. Serial No. 303,551.

This difliculty Patented. Nov. 20, 1906.

any displacement of the material round the core. The amount of currentand length of heating may also be regulated so as to prevent thecylinder from becoming too plastic,

or the furnace may be rotated on a horizontal axis during fusion. In thealternative the heating-core may be placed vertically, and the furnacemay be mounted so as to be reversible. The cylinder, and in consequencethe products formed therefrom by drawing or otherwise manipulatingduring plasticity, are usually rough on the exterior, owing to theimperfect fusion of the outer layer of silica. In order to produce anexternallyglazed product, means may be provided either for limiting theamount of material.

surrounding the'core, so that the whole of it is fused, orthe roughcylinder may be subsequently treated in a separate furnace, as describedhereinafter.

In order to limit the amount of material around the heated core, we mayprovide a jacket of carbon or other sufficiently-refractory materialas,for example, metals of the platinum grou -this jacket being furtherrotected on t e outside against heatlosses y additional sand or otherheat-insulating material. The jacket ma be made in two parts, so as tobe more easi y removable.

Where a cylindrical product is required and a jacket is employed, thevertical form of furnace is preferable, asit facilitates the feeding inof the sand or other form of silica to compensate for the shrinkage involume during fusion. When the fusion is com lete, the plastic cylinderis ready for remova and subsequent treatment. For this urpose theterminals at either end of the eatingcore are drawn apart, so as to freethe core from the furnace, and one or both ends of the sistance materialfixed between two terminals and heated by the passage ,of an electriccurrent. The tube is covered With a suitable insulating material toprevent heat losses. For some purposes this may conveniently be of sand,which, owing to the fact that it fuses external resistance due toexternal chilling.

"cording to the purpose for which it is required,

the vertical arrangement being preferable where a cylindrical product isrequired, so as to take advanta e of gravity. The rotation of thecylinder of plastic material may be employed to insure uniformity ofheating and also to help in producing a cylindrical prodnet. Themanipulation of the plastic cylin der varies with the product requiredbut in every case in which expansion of the plastic mass is required itis necessary to apply sufficient initial force to overcome the Where theinitial resistance has been overcome, the mass becomes more plastic, soas to be easily expanded.

First. To draw the cylinder, (without blowing,) the cylinder is claspedat both ends by tongs and drawn out. Rotation of the cylmder durindrawing may be employed to maintaint e-cylindrical form, and, ifdesired, the external jacket, if any, need not be re moved prior to thedrawing operation.

Second. For blowing the cylinder a nozzle constructed of a materialcapable of withstanding the high temperature or cooled by some device isinserted in one end of the plastic cylinder after withdrawing the heatedcore and the plastic mass pressed round this nozzle by some suitablemeans, so as to make a gas-tight joint at this pointe. 9.. the pressingmay be done by means of tongs which may be conveniently 1n one plecewith the nozzle-and so constructed that by closing the jaws a uniformpressure is exerted on the plastic cylinder round the nozzle. Theopposite open end of the cylinder is simultaneously closed by pressure,either by suitablyconstructed tongs, which may, if desired, be madeto-shear off the irregular end roduced,

' or by the end pressure of a suitab y-formed die, or both. The cylinderis then removed from the melting-furnace and, where necessary, freedfrom the surrounding sand, and,

where desirable, glazed in' the tubular or second furnace beforementioned. Comressed air or other gas may be admitted into the plasticmass. whichmay' then be blown out either freely or into a surroundingmold. If desired, the plastic cylinder may be simultaneously drawn whilegas-pressure is-admitted to the interior of the plastic mass,

so as to produce tubing of larger internal di a-meter or to insure itscylindrical form.

Third. The plastic cylinder ma further be compressed between suitablerol ers or dies,

so as entirely to weld up the interior cavity and produce a homogeneousmass of any desired form.

Referring now to the drawings, Figures 1' and 2 are ongitudinalelevation and plan, respectively, of a furnace in part section adaptedfor the production of a cylinder of plastic silica and means forseparating the terminals and the heating-core fronr the product aftercompletion of the fusion. Figs. 3 and 4 are longitudinal elevation andplan, respectively, of a furnace in part section capable of beingrotated with means for sep-, arating the terminals from the fusedmaterial when required. Figs. 5 and 6 are longitucfinal elevation andplan, respectively, of a furnace in part section capable of beingrotated on a horizontal transverse axis into a vertical or horizontalposition or of com pletely reversing, with means for separating theterminals from the fused material and also exemplifying themethod oflimiting the amount of material by surrounding it with a jacket toproduce fusion throughout. Fig. 7 is a longitudinal elevation showingthe same furnace rotated into a vertical position.

In Figs. 1 and 2 the heating-core a consists of a rod of graphite orhard carbon which fits between the terminals 1) of graphite or carbon.In order to insure the heated core being removed at one end along withthe terminal, the rod may be more securely at tached to one terminalthan to the other. The terminals are held in metal holders 0, supportedon metal stands, to which the current may be led by flexible leads. (Notshown.) The stands are made to slide in insulated transverse guides 11,while the transverse guides themselves can slide along longitudinalguides e. A trough f serves as a containing vessel for the material tobe fused and may be of any convenient material. The ends 9 of thetroughmay be made removable, so as to facilitate the manipulation of theplastic cylinder when required.

The followin is an example of a method of operation: graphite rodtwenty-four inches long and one inch diameter is fixed between theterminals in the manner described and covered with glassmakers sand.About one thousand amperes at fifteen volts are passed through the rodfor half an hour, when a cylinder of fused silica forms round the core.The fusion being effected, the current is cut off and the terminalsdrawn back along the longitudinal guides, the graphite core coming outalong with the terminal. When the terminals and core are convenientlyclear of the furnace, they are pushed along the transverse guides d andthe plastic cylinder is ready for subsequent manipulation.

The above figures for current, voltage, and length of heating can, onlybe taken as a rough approximation and would vary according to thematerial of which the heatingcore is composed. In order to effect thewithdrawal of the heating-core, it is necessary, however, to carryontheheating sufficiently long to effect the initial separation betweenthe heating-core and fused material by internal generation of gasor tobring about this spear'ation by the introduction of as or air betweenthe heating-core and the used material by somedevice-such as, forexample, by usin a hollow and perforated core and passing t erequiredquantity of gas through it into the middle ofthe fused mass,

as described in specification No. 812,399 of February 13, 1906. In Fig.3 the heating-core a, embedded in the material to be fused, is fixedbetween the terminals 1) in the manner described above. h representsmetal sleeves through which the electrodes ass. The sleeves are made intwo parts, wit insulating material i between. The flanges on the sleevesform the ends of the chamber f, in which the fusion is carried out andare held in position by the wedges k represents metal disks which dip'into the mercury-troughs Z, to which the current is led by means offlexible leads (not shown) and convey the current to the terminals. mrepresents the bearings on which .the furnace rotates. By means of thelongitudinal and transverse guides e the terminals can be drawn clear ofthe furnaces when required. The chamber f itself rotates in the bearingsm, which support it when the terminals are drawn apart. It is fittedwith a cover 0, which opens on hinges.

The method of operation is similar to that described above. For example,,current is passed through a heating-core fixed between the terminalsuntil a cylinder of plastic silica" of the re uired dimensions has beenformed. During t e heating the furnace is kept in slow rotation orrotated from time to time, as desired. The fusion bein complete, thecurrent is cut off and the we ges removed, so that the terminals arefree. The terminals and heating-core are then separated from the fusedmaterial in the manner described above, and after 0 ening up the chamberthe plastic silica is ready for further manipulation.

In Fig. 5, f is a metalchamber made in two parts. The terminals 1) passthrough metal sleeves h, which are madein two parts with insulatingmaterial '5 between. The flanges on the sleeves form the ends'of thechamber and are held in position by the clips'p. g

Y represents trunnlons on which the furnace I rotates. The sleeves haveextension-pieces 1", which are arranged so that they can engage with theblocks .9, which run on the transverse guides 11. Longitudinal guides eare also proprovided, as before.-. Current is led to the sleeves bymeans of flexible leads, (not shown;) but if the furnace has to rotatecompletely brushes or some. similar device for conveying the current tothe sleeve may be made to engage with the blocks.

The method of operation is similar to that described above. The heatingis carried out with the furnace in the vertical position, and whencomplete the furnace is rotated to the horizontal and the extension onthe sleeves h The clips 19, holding the sleeve-flanges at the end of thefurnace-casing, are then opened and the terminals drawn apart.

If a material glazed throughout is required, a jacket of carbon or othersufficiently-refractory material may be made to surround the core, so asto limit the amount of material-to be fused. The jacket may be used withany of the types of furnace and is shown attin Figs. 5 and 6. may beleft unjacketed, if desired, as shown' on the right of Fig. 5, in orderto facilitate the manipulation of the plastic cylinder,-or in order toprevent the material within the jacket from being blown out at theunjacketed ends the ends of the core may be surrounded with a jacket to(see Fig. 6) of slightly larger diameter, so that fusion of the outerlayer of the contained material does not take lace during the mainfusion, so that the en jackets are easily removed. One of theextension-jackets may be made funnel-shaped to enablefresh material tobe fed in.- The jacket may be made in two halves to facilitate itsremoval afterward, in which case the material surrounding the jacket onthe outside, which The ends of the heating-core serves asheat-insulator, may be of some refractory material which does not meltat the required temperature-as, for example, magnesia, carborundum, orthe like. In using a jacket it may be advantageous to use a holowheating-core and terminal and to provide means for regulating the amountof gas given off during the heating. As an example of the method oflimiting the 'amount of material around the heatingcore a graphite rodtwenty-fourinches long and one inch diameter is fixed in positionbetween terminals, with a cylinder of agglomerated carbon three inchesinternal diameter supported centrally round it, and .the whole-of thefurnace filled with pure glassmakers sand. One thousand am eres atfifteen volts are passed through unti the sand on the exterior of thejacket begins to agglomerate, which occu ies about three-quarters of anhour. The rnace is then rotated into a horizontal position andconnection made with the arrangement for separating the terminals. -Thebody of the furnace is opened, and after cutting off the current theterminals are separated, and

the 'lastic cylinder contained in the jacket is rea y for subsequentmanipulation. 4

According to the alternative method of producing'a material glazedthroughout the plastic'cylinder after removal from the furnace isimmediately transferred to an electricallyheated chamber-as, forexample,-the tubular furnace -before mentioned-wherefit is subjected toradiant heat suflicient to melt the exterior layer of agglomeratedmaterial. As soon as the glazing has been effected the plastic cylinderis ready for subsequent manipulation.

By this invention, therefore, We provide a means whereby fused silica,which on account of its high melting-point cannot be Worked by the usualprocesses common to glassmakingnamely, of melting in a receptacle andgathering portions of fused material on a blowing-tube-is brought tosuch a condition that it can be Worked into various articles withcomparative ease and while still plastic. Further, the process is one ofhigh thermal efficiency, because, in the first place, practically onlythe exact amount of material required need be fused and, secondly,because the heat is applied directly to the center of the material to befused, so that (except in the subsidiary process of glazing) practicallyno heat is lost in heating the containing vessel.

What is claimed is- 1. In apparatus for Working fused silica or thelike, a furnace, terminals therein, and a resistance-core so connectedthereto as to permit of the removal of the core from the fused mass, sothat the fused mass can be removed from the furnace during plasticity,substantially as and for the purposes set forth.

2. In apparatus for Working fused silica or the like, a furnace, a.jacket therein for limiting the amount of material to be fused,terminals in the furnace and a resistance-core so connected thereto asto permit of the removal of the core from the fused mass Within thejacket, and ofthe fused mass from the furnace during plasticity,substantially as described.

3. In apparatus for Working fused silica or the like, a furnace,terminals therein, a resista-ncecore"so connected thereto as to permitof the removal of the core from the fused mass, so that the fused masscan be removed from the furnace during plasticity, and

means for rotating the furnace, substantially as described In testimonywhereof we have hereunto set our hands in the presence of twosubscribing Witnesses.

JAMES FRANCIS BOTTOMLEY. ARTHUR IAGET.

Witnessesito the signature of James Francis Bottomley:

R. CLARK, WM. KENNEDY.

Witnesses to the signature of Arthur Paget:

H. D. JAMESON, A. N UTTING.

